The present invention generally relates to packages for hermetically sealing consumable products between generally opposing panels. More particularly, the invention relates to these types of packages which include a peelable seal that secures together at least a portion of the sealing interface between the generally opposing panels. The peel seal incorporates a tamper-evidence feature which conveys a message to the consumer when the peel seal is broken.
Packages having generally opposing panels for hermetically sealing any number of various products are well known. Also well known are packages of this type which incorporate a so-called peel seal. Peel seals can provide a hermetic seal that is suitable for vacuum packaging, for gas-flushed packaging, or other packaging wherein it is important to maintain a closure that will substantially prevent air or gas from entering or leaving the package through the seal, while at the same time provide a seal which can be conveniently opened by the application of digital forces.
Packages of this type provide a convenient and effective means for packaging, distributing and marketing a wide variety of products which would otherwise not exhibit the shelf life that is needed for these products, including those which are intended for human consumption. As exemplified by U.S. Pat. No. 3,647,485, a hermetic breakaway or peelable seal can be formed between an ethylene-polar monomer polymer film or coating and a thermoplastic film. U.S. Pat. No. 3,740,237 describes enclosing a product between a pair of films so as to provide a package having a product enclosing portion and a peripheral flange, and the pair of films are joined to form a hermetic dual seal by applying a continuous strip of peelable bond adhesive through a portion of the film in order to provide the peel seal of that patent. U.S. Pat. No. 4,273,815 describes a laminated film having at least one lamina of polyvinylidene chloride film adhered to at least one lamina of chlorinated polyethylene. Sometimes peel seals are combined with features for providing a reclosable package, such as by incorporating an interlocking strip assembly at a location generally proximate to the peel seal. Examples of patents in this regard include U.S. Pat. No. 4,782,951 and U.S. Pat. No. 4,823,961. The subject matter of all of these patents is incorporated by reference hereinto.
One of the sometimes perceived shortcomings of packages incorporating peel seals is that it is often not readily apparent to the casual observer that the peel seal has been opened. This situation can be further complicated when the package closure arrangement includes members that can be opened and reclosed without ready detection thereof, which is typically the case when reclosable interlocking strips are used. Various approaches have been taken or proposed in order to ensure detection of seal opening or tampering. Exemplary of the various techniques which have been known for providing visual, tamper-evident features on packaging include U.S. Pat. No. 3,780,781, U.S. Pat. No. 4,015,771 and U.S. Pat. No. 4,786,190. A copending application directed to tamper-evident arrangements in flexible packages and the like is U.S. patent application Ser. No. 419,695 of Hustad, filed Oct. 11, 1989.
Developments of this type address the fact that, but for the tamper-evident members provided thereby, a package which has been opened and thereafter reclosed would have an outward appearance comparable to a package which retains its hermetic peel seal, and this opening and reclosing could not be readily detected unless all or a noticeable portion of the contents of the package have been removed. Of course, the likelihood of detection of a package that had been opened and reclosed would be greater for vacuum-packed products because the distinctive product-conforming shape of a vacuum package would be modified in a manner that should be discernible to most knowledgeable consumers. Determining that a package which is not vacuum sealed, such as a gas-flushed package, had been previously opened usually would be more difficult. Many of the tamper-evident means that have been provided or proposed heretofore incorporate a supplementary component such as a tear strip, an extra tab, or the like. Generally, these complicate the package sealing procedure and/or increase the cost of the package.
Accordingly, there is a need for a package of this general type which possesses the convenience of incorporating a peelable seal that is readily opened by the application of digital forces and that provides readily discernible evidence that the peelable seal has been broken, but without the need for adding panels, tabs, tear strips, paper components, tapes and the like. It is important that this need be fulfilled by means which make it readily apparent to the consumer in the store (that is, before the package is purchased by the consumer) that the package had been previously opened or that its peel seal had been otherwise tampered with. This package must be suitable for products intended for human use or consumption, including various food products such as wieners, bacon, sliced luncheon meats, chops, cheese and the like.
In summary, the packages according to the present invention are for hermetically sealing products between generally opposing panels which provide a substantially airtight seal of the product within the package. At least a portion of the seal joining the panels together has peelable properties such that access to the products within the package can be gained by breaking the peelable seal. This peelable seal itself includes tamper evidence means such that breaking of the seal is signaled by a readily discernible modification in the appearance of a message component of the peelable seal area. A background portion of the peelable seal area has a contact clarity condition that is disrupted to an opacity condition in order to create message indicia at the peel seal area, which message indicia inform the purchaser that the peel seal is no longer fully intact. The message indicia are defined by indicia engraved into the heat seal bar which forms the peelable seal.
It is accordingly a general object of the present invention to provide an improved tamper-evident package having a peel seal.
Another object of the present invention is to provide an improved tamper-evident package which incorporates message indicia within the peel seal area in order to directly inform the consumer or prospective purchaser that the peel seal has been opened.
Another object of this invention is to provide a tamper-evident package and method which achieves a tamper-evident objective without requiring added panels, tabs, tear strips and the like.
Another object of the present invention is to provide an improved product package and method that utilizes peel seal means which exhibit a contact clarity condition prior to opening and an out-of-contact opacity condition which creates message indicia that directly indicate the seal has been broken.
Another object of this invention is to provide an improved product package that incorporates a peel seal having tamper-evidence characteristics without incurring any, or only minimal, cost upcharge.
Another object of the present invention is to provide an improved peel seal tamper-evidence characteristic for packages incorporating a procedure using an engraved heat seal bar.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.